The present invention relates to a heating system for occupant spaces of power vehicles with liquid-cooled internal combustion engines.
During starting a vehicle motor after a long period of non-driving, first no heating energy for the occupant space is available. For example in modern PKW diesel motors which operate with high efficiency, such operational conditions are possible in which no sufficient heating energy is produced over long distances of travel. For such instances a cost-effective additional heating device is an advantageous alternative, which operates in satisfactory manner but involves expensive stationary heating.
The present invention deals with a heating system in which an element which is rotatably driven by the internal combustion engine is arranged in a medium-filled chamber and associated with a stationary structural part so as to form at least one gap therebetween. The heating system of this type is known for example from the German document DE-OS 1,476,328. In this system a heating aggregate is connected parallel to a cooling medium circulating circuit for the internal combustion engine and includes a substantially a fuel consuming burner and a boiler. For supplying hot water to a heat exchanger for the vehicle heating, the water must be heated in the boiler to steam generation. A filling of the boiler with cold water from the water casing of the internal combustion engine is performed after sinking of the water level in the boiler and releasing the steam in the water casing through a float valve. Such a heating arrangement operates in a varying fashion and its operational process is complicated. Furthermore, in certain operational conditions of the known combustion engine the heating output of the heating system is imperfect.
Another known heating system disclosed in the German reference DE-OS 3,147,468 operates in accordance with the principle of the hydrodynamic rate. In this system cooling water accelerated by the impeller is delayed in the impeller chamber of the stator. The kinetic energy is directly converted into heat in the rotating cooling water volume, so that a relatively high efficiency is achieved. The disadvantage is however that the heating systems working on the principle of hydrodynamic brake have such an output characteristic which is dependent on the third power of the drive number of revolutions. Therefore in the region of low number of revolutions a proportionally low heating output is produced.